How does this formula relate to functional programming?

Question

Programming

The formula itself:

Thank you for your answers.

Answer 1

Composition of functions f and g

Answer 2

none at all.
Functional programming is a paradigm, not code itself.

Answer 3

the picture is an illustration of the differences between the functional and imperative approaches. More specifically, what is the difference, and which arrows can be attributed to which approach, you will read already where you found this picture.